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      <title>如何在Java中优雅地处理异常与回调 - 交互式测验</title>
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    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>如何在Java中优雅地处理异常与回调 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
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                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "根据文档，Java中的“未受检查异常 (Unchecked Exception)”通常是由什么原因引起的？",
    "options": [
      "程序的逻辑错误，例如 `NullPointerException`。",
      "必须由程序员在编译时处理的错误。",
      "资源不可用，例如文件不存在。",
      "外部系统故障，例如网络连接中断。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "文档明确指出，未受检查异常（Unchecked Exception）通常由程序的逻辑错误引起，例如空指针引用（NullPointerException）或数组越界（ArrayIndexOutOfBoundsException）。这类异常在编译时不会被强制检查，与必须处理的受检查异常（Checked Exception）相对。",
    "source": "文档中「1.2 异常的分类」部分",
    "hint": "文档中提到了 `NullPointerException` 和 `ArrayIndexOutOfBoundsException` 作为这类异常的例子。"
  },
  {
    "question": "在Java的`try-catch-finally`结构中，`finally`代码块的执行时机是什么？",
    "options": [
      "只有当`try`块中的代码成功执行，没有发生任何异常时才执行。",
      "无论`try`块中是否发生异常，`finally`块中的代码总会被执行。",
      "只有当`try`块中发生异常并被`catch`块成功捕获时才执行。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "`finally`块的设计目的是确保某些代码（如资源释放）无论程序执行路径如何都能被执行。因此，不管`try`块是正常完成还是因为异常而中断，`finally`块都会在其后执行，是进行清理工作的理想场所。",
    "source": "文档中「1.3 异常处理的流程」部分",
    "hint": "想一想 `finally` 块最常见的用途是什么，比如关闭文件或数据库连接。"
  },
  {
    "question": "根据文档，在复杂的系统中定义自定义异常类（如`DatabaseException`）的主要好处是什么？",
    "options": [
      "让所有异常都变成未受检查异常，从而无需在方法签名中声明。",
      "对错误进行更细粒度的分类，从而可以根据不同的异常类型执行不同的处理逻辑。",
      "减少代码中`try-catch`块的使用。",
      "统一所有异常类型，用一个`catch`块处理所有错误。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档中提到，定义自定义异常类可以“对错误进行更细粒度的分类”。通过创建如`DatabaseException`和`NetworkException`这样的特定异常，可以在`catch`块中针对每种具体的错误情况编写不同的、更精确的处理代码，增强了系统的鲁棒性。",
    "source": "文档中「2.2 定制化异常处理」部分",
    "hint": "思考一下为什么在`try`块后面可以跟多个`catch`块，每个`catch`块捕获不同类型的异常。"
  },
  {
    "question": "相较于传统的接口实现方式，Java 8的Lambda表达式为回调机制带来了什么主要优势？",
    "options": [
      "提高了回调的执行性能，使其运行速度快数倍。",
      "使回调的实现代码更加简洁和紧凑。",
      "彻底取代了接口，使得接口在回调中不再被使用。",
      "增加了回调的类型安全性，防止运行时错误。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档通过代码示例对比了传统接口实现和Lambda表达式。使用Lambda表达式，可以将原本需要通过匿名内部类实现的冗长回调方法，简化为一行或几行代码，显著提高了代码的可读性和简洁性。",
    "source": "文档中「3.2.2 使用Lambda表达式简化回调」部分",
    "hint": "查看文档中 `executeTask` 方法的两个不同调用示例，对比它们的语法差异。"
  },
  {
    "question": "在Java 8的`CompletableFuture`中，`handle`方法的主要作用是什么？",
    "options": [
      "专门用于在任务开始前设置回调函数。",
      "只能用于处理任务成功时的返回结果，无法处理异常。",
      "在异步任务完成时（无论成功还是出现异常），统一处理结果或异常，且不阻塞主线程。",
      "它是一个同步方法，会阻塞主线程直到异步任务完成。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "`handle`方法接收一个函数作为参数，该函数有两个输入：任务结果和异常。如果任务成功，结果非null，异常为null；如果任务失败，结果为null，异常非null。这使得我们可以在一个地方优雅地处理异步任务的两种最终状态，提升了代码的健壮性和性能。",
    "source": "文档中「4.2 异常处理中的回调增强：CompletableFuture」部分",
    "hint": "文档中提到 `handle` 方法允许在异步操作完成时处理“结果或异常”。"
  },
  {
    "question": "文档中提到的“异常的封装与转换”是一种最佳实践，其主要目的是什么？",
    "options": [
      "直接将底层异常（如`SQLException`）抛出到最上层，让调用者了解所有细节。",
      "将所有异常都转换为`RuntimeException`以简化代码，避免使用`try-catch`。",
      "避免在高层业务逻辑中暴露底层实现细节，将底层异常转换为更具业务含义的自定义异常。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "这种实践的核心思想是解耦和抽象。通过将底层的技术性异常（如`SQLException`）封装成业务相关的自定义异常（如`DatabaseException`），可以隐藏实现细节，使上层代码只关心业务层面的错误，从而提高系统的可维护性和一致性。",
    "source": "文档中「5.1 异常的封装与转换」部分",
    "hint": "这种做法可以“隐藏实现细节”，并使系统保持“一致性”。"
  },
  {
    "question": "为了提高回调的可维护性和灵活性，文档推荐使用哪种设计模式来解耦回调逻辑与业务逻辑？",
    "options": [
      "工厂模式（Factory Pattern）。",
      "单例模式（Singleton Pattern）。",
      "代理模式（Proxy Pattern）。",
      "观察者模式（Observer Pattern）或事件驱动架构。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "文档明确指出，为了解耦，可以使用“观察者模式”或“事件驱动架构”。这些模式允许一个对象（发布者）在状态改变时通知多个依赖它的对象（订阅者或监听者），从而将回调的实现与业务逻辑分离，使代码更灵活和可扩展。",
    "source": "文档中「5.2 回调的解耦」部分",
    "hint": "文档中提供了一个 `EventPublisher` 和 `EventListener` 的代码示例来说明这个概念。"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
        // 存储每个问题的回答状态
        const userAnswers = new Array(quizData.length).fill(null); 

        const questionTextEl = document.getElementById('question-text');
        const optionsListEl = document.getElementById('options-list');
        const resultContainerEl = document.getElementById('result-container');
        const quizContentEl = document.getElementById('quiz-content');
        const progressIndicatorEl = document.getElementById('progress-indicator');
        const prevBtn = document.getElementById('prev-btn');
        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

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          optionsListEl.innerHTML = '';
          hintContainerEl.style.display = 'none'; // 隐藏提示
          
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            showFinalScore();
            return;
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            li.textContent = optionText;
            li.dataset.index = index; // Store index in a data attribute
            // 如果这道题已经回答过，恢复状态
            if (userAnswers[currentQuestionIndex] !== null) {
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                    li.classList.add('selected');
                }
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            optionsListEl.appendChild(li);
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          // 如果已经回答过，直接显示结果
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              showResult(isCorrect, currentQuestion);
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          updateNavigationButtons();
          updateProgress();
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        function selectOption(optionIndex) {
            userAnswers[currentQuestionIndex] = optionIndex;
            const currentQuestion = quizData[currentQuestionIndex];
            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

            // 重新计算分数
            score = userAnswers.reduce((acc, answer, index) => {
                return answer === quizData[index].correctAnswerIndex ? acc + 1 : acc;
            }, 0);

            showResult(isCorrect, currentQuestion);
            updateNavigationButtons();
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            nextBtn.style.display = 'block';
            hintBtn.style.display = 'block'; // 显示提示按钮

            prevBtn.disabled = currentQuestionIndex === 0;
            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
            nextBtn.textContent = (currentQuestionIndex === quizData.length - 1) ? '查看报告' : '下一题';
            
            // 如果当前问题没有提示，则禁用提示按钮并隐藏提示内容
            if (!quizData[currentQuestionIndex].hint) {
                hintBtn.disabled = true;
                hintContainerEl.style.display = 'none';
                hintContainerEl.textContent = ''; // 清除旧的提示内容
            } else {
                hintBtn.disabled = false;
            }
        }

        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
            resultContainerEl.appendChild(resultBox);

            // 禁用所有选项的点击事件，并高亮正确/错误答案
            Array.from(optionsListEl.children).forEach((child, index) => {
                child.style.pointerEvents = 'none';
                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
                    child.style.backgroundColor = '#f8d7da';
                    child.style.borderColor = '#f5c6cb';
                }
            });
        }

        function goToNextQuestion() {
            if (currentQuestionIndex < quizData.length - 1) {
                currentQuestionIndex++;
                loadQuestion();
            } else {
                showFinalScore();
            }
        }

        function goToPreviousQuestion() {
            if (currentQuestionIndex > 0) {
                currentQuestionIndex--;
                loadQuestion();
            }
        }
        
        function showHint() {
            const currentQuestion = quizData[currentQuestionIndex];
            if (currentQuestion.hint) {
                hintContainerEl.textContent = currentQuestion.hint;
                hintContainerEl.style.display = 'block';
            } else {
                hintContainerEl.style.display = 'none';
            }
        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  